Thursday, January 11, 2007

Deja Vu...

MSN has an article on 99942 Apophis (formerly known as 2004 MN4). There's nothing wrong with the science of the article. There are a few bits of the article that I think are pretty nice.

The first is the mention of the Yarkovsky effect. This effect occurs when an object absorbs light on one face, but then rotates and reemits that radiation in another direction. The radiation being emitted exerts a very weak force in the opposite direction. But although the force is weak, it can go on for a very long time, and can significantly alter the orbit of objects.

Another part I really liked was the conclusion that, should it be necessary, we can build a probe to nudge Apophis slightly off course. And it's relatively cheap: a mere $250 million (the two Mars rovers Spirit and Opportunity cost about $850 million). The article states:
Ironically, that's almost precisely the cost of making the cosmic-collision movies Armageddon and Deep Impact. If Hollywood can pony up a quarter of a billion in the name of defending our planet, why can't Congress?

But what is rather strange about the article, is the timing. It's old news. In fact, I've already commented on how old it is. It doesn't say anything that we haven't been saying since December 04 (the time when the asteroid's trajectory was known well enough to rule out a 2029 impact). So why the sudden urge to post this story again?

I have no idea. It seems that astronomy stories are just so good that they have to be retold year after year...

Speaking of which, who wants to take bets on when we'll hear the first mention that this August, Mars will look as big as the full moon to the unaided eye?

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